chr11-68933899-C-A

Variant names:

• chr11-68933899-C-A
• rs754465226
• NM_002180.3:c.1523C>A

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1 PM2

The NM_002180.3(IGHMBP2):​c.1523C>A​(p.Ser508*) variant causes a stop gained change. The variant allele was found at a frequency of 0.000000694 in 1,440,930 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. S508S) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: IGHMBP2 NM_002180.3 stop_gained
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 7.15
• Publications: 0 publications found

Genes affected

IGHMBP2 (HGNC:5542): (immunoglobulin mu DNA binding protein 2) This gene encodes a helicase superfamily member that binds a specific DNA sequence from the immunoglobulin mu chain switch region. Mutations in this gene lead to spinal muscle atrophy with respiratory distress type 1. [provided by RefSeq, Jul 2008]

IGHMBP2 Gene-Disease associations (from GenCC):

• autosomal recessive distal spinal muscular atrophy 1

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Ambry Genetics, Genomics England PanelApp, Orphanet, Labcorp Genetics (formerly Invitae)
• Charcot-Marie-Tooth disease axonal type 2S

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Laboratory for Molecular Medicine, Orphanet, Ambry Genetics, Labcorp Genetics (formerly Invitae)
• hereditary peripheral neuropathy

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
IGHMBP2	NM_002180.3	c.1523C>A	p.Ser508*	stop_gained	Exon 10 of 15	ENST00000255078.8	NP_002171.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
IGHMBP2	ENST00000255078.8	c.1523C>A	p.Ser508*	stop_gained	Exon 10 of 15	1	NM_002180.3	ENSP00000255078.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.94e-7 AC: 1 AN: 1440930 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 714916

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33108

American (AMR) AF: 0.00 AC: 0 AN: 41740

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25732

East Asian (EAS) AF: 0.00 AC: 0 AN: 39034

South Asian (SAS) AF: 0.00 AC: 0 AN: 83478

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52142

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5734

European-Non Finnish (NFE) AF: 9.09e-7 AC: 1 AN: 1100436

Other (OTH) AF: 0.00 AC: 0 AN: 59526

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.65
CADD	Pathogenic	39
DANN	Uncertain	0.99
Eigen	Pathogenic	0.72
Eigen_PC	Uncertain	0.54
FATHMM_MKL	Pathogenic	0.99	D
PhyloP100		7.1
Vest4		0.84
GERP RS		4.8
Mutation Taster		=2/198	disease causing (fs/PTC)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs754465226; hg19: chr11-68701367;